1. Field of the Invention
This invention relates to a seed planter drum drive system and more particularly to a system which can be readily adjusted to obtain a desired seed spacing and which accurately maintains the desired seed spacing. The system is relatively simple and straight-forward in construction and operation and is highly reliable.
2. Description of the Prior Art
Seed planters have heretofore been provided in which seed from a hopper is fed to a revolving seed drum with air under pressure being supplied to the interior of the drum to cause seeds to be picked up in perforated pockets in the periphery of the drum as the drum rotates, the pocketed seeds being released when they reach the top of the drum by seed-release wheels blocking the perforations of the pockets. The seeds then drop into delivery tubes, being propelled therethrough by the pressurized air to be delivered into a furrow opened by a furrow-forming structure. In such arrangements, the drums have been rotated at a speed proportional to the speed of travel of the planter over the ground and the population density of the seeds is fixed in such cases, being changable only by changing the drum. Proposals have been made for controlling the speed of operation of a seed dispenser to change the seed population density but such proposed systems have been relatively complex. For example, the Steffen U.S. Pat. No. 3,912,121 discloses a system in which a DC control motor is connected to a transmission which in turn is connected to a torque amplifier of a hydraulic system controlling the rate at which the seed dispenser is operated, the DC control motor being connected to electronic circuitry.